It has long been desired to produce a simple device which transmits linear motion of one member directly into rotary motion of another member. This is particularly desirable in an oil pressure transducer as used in vehicles with internal combustion engines. The object of a device of this kind is to accurately transmit the pressure level of oil in the engine with a device of simple construction with few parts and great reliability.
An early pressure indicator is disclosed in U.S. Pat. No. 1,171,480 to Troll. In the Troll patent, a linear moving member attached to a diaphragm transmits the linear movement to rotary movement by means of a lever and gear arrangement. The mechanism is relatively complex as opposed to the subject device to be described hereinafter.
Another relatively early device is shown in U.S. Pat. No. 2,877,327 to Hastings. The Hastings device utilizes a movable diaphragm member responsive to liquid pressure. The diaphragm member includes a linearly movable portion with an axial aperture therethrough. A pin with a spiral channel formed therein moves in the aperture and is rotated by means of a follower which extends into the channel. While producing rotary movement directly from linear movement, the Hastings patent provides an entirely different structure than the subject device.
Other patents known to applicant are as follows: U.S. Pat. Nos. 4,086,557; 2,943,302; 2,286,717; 4,449,113; 3,160,014; and 2,525,095. None of the aforementioned pressure indicators of transducers utilize the structure of the subject device to be described hereinafter.